The invention relates to an instrument for manual operation comprising a stem, an attendant member disposed at a distal end of the stem, and a hand grip having a substantially round shape disposed at a proximal end of the stem.
Such an instrument is known from practice and is employed in numerous situations. As examples could be mentioned gardening tools, carpenter's tools, (electrical) toothbrushes, paint scrapers and in general all the devices that are provided with a hand grip to facilitate handling.
Many of the instruments for manual operation have handgrips that are not ergonomically shaped. A handgrip is often held in one way, but occasionally objects need to be held in different grip attitudes (underarm, overarm, obliquely underarm and obliquely overarm). If tensile forces have to be exerted with the instrument, a good grip is vital.
Firstly, to avoid fatigue striking too quickly and secondly, to be able to exert the necessary force while spending as little energy as possible.
An instrument of the kind referred to in the preamble, wherein the hand grip is fixed in the extended direction of the stem, and in which the stem is placed eccentrically in relation to the hand grip, such that the body of the hand grip has an axis that runs next to the axis of the body of the stem, at a side away from the attendant member, is known from U.S. Pat. No. 5,586,989. This concerns a curette for microsurgical applications.
Hereinbelow the invention will be further elucidated by way of an example of a retractor to be used in surgery. However, the invention must not be considered to be limited to the example given below, but rather relates to all possible applications in which an instrument for manual operation can be employed.
The retractors that have been available on the surgical market for more than a century, have not changed for decades. For example, one retractor known from the prior art is shown in DE-A-2455625. Medical problems related to the supporting and locomotor apparatus are widespread in the health care sector due to, among other things, poor posture while performing surgery. Complaints of neck and shoulders are particularly prevalent. When holding open a wound, the assistant handling the retractor is called upon to exert (considerable) static forces. For the surgeon it is important that the wound be held open properly from the beginning of the surgical procedure to the end. This varies from several minutes to an hour.